1. Field
The invention is in the field of positive displacement, pressure fluid powered, piston and cylinder engines capable of directly accommodating varying power needs of an automotive vehicle or other motivated device, without the customary use of a separate power transmission mechanism.
2. State of the Art
A variable piston stroke and variable cylinder capacity engine, which can directly accommodate varying power needs without the usual separate automobile transmission, is disclosed in my U.S. Pat. No. 4,401,010 of Aug. 30, 1983. However, there is still need for a relatively simple engine providing smooth, high torque output even at relatively slow engine speeds, as well as high overall power output and the typical functions of an automobile transmission, namely forward and reverse drives, and the neutral and park functions.
In the making of the present invention, a principle objective was to provide an engine which requires no transmission and which is capable of providing a high torque output independently of engine speed, so the engine can be coupled directly to a load, such as a wheel or wheels of an automotive vehicle. In accordance therewith, I have taken advantage of well-known roller clutches for converting fixed piston stroke, reciprocating motion in opposite directions to unidirectional rotary motion of a power output drive shaft assembly. Power output of the engine is varied by controlling the input volume in addition to conventional pressure regulation, of a pressure fluid, such as steam or a compressed gas, to the cylinders of a pair or pairs of oppositely acting, piston and cylinder power units of the particular engine concerned.
Other objectives of the invention were to produce a piston and cylinder type of engine, which can provide the typical transmission functions of forward and reverse drives and neutral and park functions, and with smooth torque output continuously throughout the full 360 degrees of a rotation of an output drive shaft arrangement, particularly at low engine speeds; to optimize the leverage of a the pistons in rotating the drive shaft of such an engine during reciprocative strokes of the respective pistons of the power units for overall power output; to optimize the volume of a pressurized fluid such as steam or a compressed gas introduced into the cylinders such an engine so as to allow the use of a relatively small condenser when the pressure fluid is steam or other heated fluid; and to provide a simpler engine of the type concerned at an economically favorable cost.
The use of roller clutches for converting opposite reciprocative motions of the pistons of a piston and cylinder power unit pair or pairs in an engine to unidirectional rotary motion is best accomplished in accordance with the invention by the piston of each power unit of the pair or pairs thereof having a piston rod with coextensive sets of cooperating and of oppositely facing gear racks extending longitudinally thereof, one gear rack from each power unit of the pair or pairs confronting a gear rack of the other power unit of the pair or pairs, with a timing gear interengaging the two confronting gear racks. The remaining gear racks of each set interengage a pinion gear of the corresponding roller clutches which unidirectionally turn a first drive shaft, the extent of torque output being varied by controlling the volume of pressure fluid introduced into the cylinders of such power units, with specific pre-determined volumes substituting for the shifting of gears in the usual transmission of an automotive vehicle. Thus, for example, in an automotive vehicle, when the volume of pressure fluid required to operate the engine at start-up or under heavy load is one hundred percent of the volumetric capacity of the cylinders of a drive unit pair, that is the volume of pressure fluid input for the time required to cope with the load, thus corresponding to low, or first gear in the usual transmission. When the volume of pressure fluid required to cope with the load corresponding to second gear in the usual transmission is only thirty percent, that is the volume of pressure fluid input for the time required. When the volume of pressure fluid required to cope with the load corresponding to third gear in the usual transmission is only twenty percent, that is the volume of pressure fluid input for the time required. When the volume of pressure fluid required to maintain top vehicle speed corresponding to fourth or high gear in the usual transmission, as on a level road surface, is only ten percent, the volume of pressure fluid is cut down to ten percent for the time that this condition remains. The choice of ten percent, twenty percent, thirty percent, or one hundred percent volume of pressure fluid may be controlled as by a lever or switch mounted on an automotive vehicle steering column. The pressure fluid is preferably steam due to its high expandability, however, other liquids which may be vaporized, or even pressurized gases such as air, may be used.
Forward and reverse drives and neutral and park functions are provided for automotive applications, such as in directly powering the wheels of an automotive vehicle. The reverse drive function is achieved by incorporating a third, and a pistonless fourth power unit, or reversing unit, along with the usual pair of unidirectional forward power units, and a second pair of oppositely rotating roller clutches which engage a second drive shaft so as to rotate it oppositely to the first drive shaft. These first and second drive shafts are selectively coupled, as by means of a sliding clutch and gear assembly, through a geared differential mechanism, to a pair of jackshafts, each of which have one wheel of the vehicle attached for rotation therewith, the engine thus effecting the several functions of the usual automotive transmission mechanism. The engine may also incorporate a foot-actuated, pressure fluid throttle valve to vary the pressure of the pressure fluid entering the engine, similar to using the throttle pedal on an automotive vehicle.